The Impact of Male Sensory Cues on the Female Brain

K. M. Kendrick

The extent to which the female's reproductive cycle influences the impact
of male sensory cues on her brain and behaviour has mainly focussed on
her response to actual mating. Using sheep as model we have attempted to
investigate the differential effect of male visual and olfactory cues on
patterns of activation in the female brain when she is sexually receptive
as opposed to when she is not. Changes in neural activation were visualised
in ovariectomized hormone-treated females by quantifying changes in c-fos
mRNA expression after a 5 min exposure to a male. During behavioural oestrus,
exposure to males significantly increased expression in all primary and
association cortex regions involved with visual and olfactory processing,particularly
in regions of the temporal cortex associated with face recognition. Increases
also occurred in the limbic system (hippocampus CA1, subiculum, lateral
septum, basolateral amygdala and bed nucleus of stria terminalis)and regions
of the hypothalamus involved in mediating female sexual responses (mediobasal
hypothalamus and medial preoptic area). Increased expression was also seen
in the nucleus accumbens which is associated with reward. These changes
occurred independent of the male intromitting and are therefore mainly
due to distal male sensory cues. When the females were not sexually receptive
no increased c-fos expression was seen in any cortical, limbic or hypothalamic
regions excepting a small increase in temporal cortex. This occurred even
though the females experienced the same level of exposure to male cues.
These results demonstrate clearly that the female's reproductive cycle
can dramatically alter the impact of male visual and olfactory cues not
just at the level of sex hormone-concentrating neurons in the limbic system
and hypothalamus but also in the primary and association cortical regions
that relay sensory information to them.